For cleaning the cylinder of rotating drum printing equipment, it is known to have a cleaning cloth that serves to take up dirt adhering to the cylinder to be cleaned. The cloth is brought into contact with the surface of the cylinder with the help of a contacting body, with the force exerted to achieve a frictional force being produced by an activatable driving mechanism.
The contacting force must provide the required contact pressure, at which a satisfactory cleaning result is achieved. The cleaning action is based on softening or dissolving the adhering dirt particles from dye residues and paper dust with the help of solvents while simultaneously rubbing off the particles.
The dirt and solvent are carried away by the cleaning cloth used, which is pressed against the cylinder in the axially extending contact zone. The capacity to absorb dirt is limited by the structure of the cloth fabric. For this reason, new, clean strips are supplied periodically to the cleaning zone. For this purpose, a cloth advance mechanism winds the cloth from a delivery roll to a dirt roll. At the dirt roll, the dirt, taken up by the cloth, is recovered as a wrapped-up layer. As long as a strip of the cleaning cloth is pressing against the cylinder, the rubbed-off dirt is collected and accumulated.
In the gap between the cloth and the cylinder, in which dirt is accumulating or piling up, shear forces arise, by which the dirt moves through the gap immediately when the forces are relieved. If the cylinder duct passes through the contact pressure zone, the dirt penetrates into the duct depression. The "banking-up pressure," exerted in the dirt gap, also does not permit the cloth to lie properly against the cylinder and to rub off the dirt.